Saprissa earned a 1-1 draw against Alajuelense at the Estadio Alejandro Morera Soto on Monday, which was enough to see Jeaustin Campos' men triumph 2-1 on aggregate.
The San Juan de Tibas-based outfit - who scraped into the semi-finals after claiming the fourth and final play-off spot - took a slender one-goal lead into the second leg thanks to their last-gasp 1-0 win in the semi-final first leg.
Deyver Vega was on hand to net the opener three minutes before half-time, putting the visitors two goals clear via a priceless away goal.
Jose Ortiz did manage to pull a goal back for Alajuelense on the hour mark but it proved nothing more than a consolation for the home side, who topped the standings during the regular season.
Neither Herediano nor Cartagines could find the back of the net at the Estadio Eladio Rosabal Cordero as Jafet Soto's side won 3-2 on aggregate.
The final will be played over two legs, with the opener taking place at the Estadio Ricardo Saprissa Ayma on December 14.
